1. Field of the Invention
The present invention relates to an apparatus and method of converting data, and more particularly, to an apparatus and method of converting data to display smooth and vivid images and to improve the gray scale use efficiency, and an apparatus and method of driving image display devices using the same.
2. Discussion of the Related Art
Recently, various flat display devices that can overcome disadvantageous properties, including the large weight and size, of cathode ray tubes (CRT) have been developed. For example, there are liquid crystal display devices (LCD), plasma display panels (PDP), and light emitting displays (LED). The LCD device displays images by applying an electric field to a liquid crystal layer formed between two glass substrates therein, and controlling the intensity of electric field so as to control the transmittance of light through the liquid crystal layer. The PDP displays images using plasma generated by gas discharge. The LED displays images by luminescence of organic or polymer substance.
Devices including the digital camera, camcorder, and scanner convert natural images into data with a predetermined resolution. Generally, a host system including personal computer, notebook computer, and television that drives the flat display device uses digital data that are discretized into an 8 bit data. Accordingly, as shown in FIG. 1A, the gray scales of the virtual image to be displayed, in which gray scale smoothly increases from A to B, is converted into an 8 bit data, in which the gray scale increases discontinuously from A to B, as shown in FIG. 1B.
In order to display an image that is substantially identical to the virtual image using a limited resolution, i.e., 8 bit data, it is necessary to perform a compensation process using various signal processing technologies corresponding to human viewing properties. Without such compensation process, the gray scale of the image converted into the data on the basis of 8 bit input/output gamma property curve may become indistinguishable in areas where the first derivative, i.e., slope, of the gamma property curve is smaller than 1. Here, the X-axis of the gamma property curve is the 8 bit input data and the Y-axis of the gamma property curve is the 8 bit output data.
In the area where the first derivative of gamma property curve, relating the 8 bit output data to input data, is smaller than 1, as shown in area C of FIG. 2A, the input gray scales 51 and 52 are mapped to the points of output gray scale 41.2 and 41.4, shown in FIG. 2B. However, since the digital output can be represented only as the integer, the input gray scales 50, 51 and 52 are displayed as output gray scale 41. Accordingly, it is difficult to distinguish the input gray scale 50, 51, and 52 by viewing the output gray scale that is displayed. Thus, the picture quality is deteriorated in the display device due to the gray scale indistinguishability.